Embodiments of the present invention relate generally to methods and systems for tracking a mobile device and more particularly to tracking a mobile device using sensors within the device and without using external signals to determine location, velocity, or heading.
There are a variety of techniques used for determining a location of a person or, more specifically, a mobile device being carried by that person. One well-known method involves using a Global Positioning System (GPS) receiver in the mobile device that detects and triangulates globally broadcasts satellite signals. In another method, triangulation of signals from cell sites can be used to determine the location of the mobile device. In yet another method, triangulation of signals from local WiFi equipment can be used to determine the location of the mobile device. In some cases, these different methods can be augmented by using a predefined map of a particular area and the location of the device determined by these methods can be adjusted based on that map. For example, a system employed within a shopping mall for providing location-based advertisements or other functions can use a predefined map of the interior of that mall. Since a shopper cannot be standing where a wall is located and is likely not to be standing or moving through where a fountain or decorations are located, the determined location for that device can be adjusted accordingly to correct for errors.
However, each of these methods have some notable shortcomings. For example, triangulation of cell signals is not very accurate for locating and/or tracking pedestrians. GPS is more accurate but still not very accurate for locating and tracking pedestrians and is commonly unavailable indoors or in other situations. WiFi is highly localized but is available in only limited situations. In short, each of these methods relies on an external signal or devices, i.e., external to the mobile device, and that may be inaccurate, unreliable, or completely unavailable in some situations. Hence, there is a need for improved methods and systems for tracking a mobile device.